Device for equalizing strains upon a group of cables connected to a stress-receivingelement



DEVIUE FOR EQUALIZING STRAINS UPON A GROUP OF CABLES CONNECTED TO A STRESS RECEIVING ELEMENT Filed Dec. 26. 1931 2 Sheets-Sheet 1 Jan. 17, 1933. I FROST 1,894,351

Jan. 17, 1933.

Uzi 07: Zla a i at ented Jan. 17, 1933 UNI ED STATES PATENT OFFICE P2, FROST, E JACKSON HIIL ITGH'T IES,- NEW YORK; ASSIGNOB TO EVANS ELEVATOR EQUALIZEB. COMPANY, OF BEDFO BD, INDIANAgA CORPORATION OF INDIANA DEVICE FOR EQUALIZING STRAINS UPON A GROUP OF CABLES CONNECTED TO A STRESS-REC'EIVING Application filed December 26', 1931. Serial No. 588,342.

My invention relates" to a device for equalizing the strain upon the members of a group of cables or other tension members connectfor the" purpose of equalizing the strain on ly suited for such use.

such cables. In the art relating to the hoisting of passenger and freight elevator cars by means of a group of hoisting cables, it is'established practice to counterbalance the weight of the car by a counterweightconnccted to the hoisting cables on the opposite end of the cables from the car, and it is Well understood that as the cables run overthe hoistingor suspension drum between the car and counterweight the weight of the cables is transferred from one-side to'the other,'thus destroying the balance between the car and counterweightl To preserve this balance it is usual to employ a group of compensating cables engaging grooves in a common compensating pulleyat the bottom of theelevator shaft and connected: attheir opposite ends tothe bottom of the car and the counterweight, such as the arrangement: explained in my copending application for patent filed March 21-, 1930, Serial No. 437,684. My present invention will be described with reference to an elevator installation oft'his kind, and be-; cause of the limited clearance below a car at. the bottom of the elevator shaft. and the small vertical dimensions of the device it is'especial- It will be understood, however, that in inverted position, it

isalso capable of being used as an equal-1 izing. device for connecting an elevator car (or counterweight) to a group of hoisting cables,or in other situations in which a group of cables subject to joint stress are connected to a stress receiving body or element;

As is well understood in the elevator art,

differences in sizes, twist and wear of the compensating or hoisting cables employed in elevator apparatus, and alsov slight differences in the circumferential dimensions ofthe.

grooves of the compensating drum or hoistring drum cause the connected cables,i-n some instances, to=havea slightly different degreeof travel which, in the case of cables directlyattached to the car and counterweight, occa sions a difi'erence of stress upon the connected cables, and various kinds of equalizing devices for remedying this defect are known. It isthe'objectof my present invention to provide a simple, efiicient and reliable equalizing device of the type employing an equalizing cable engaging pulleys on the cable ends and car which because of its novel arrangement and combination of cooperating parts, shall possess advantages in the way of com pactness and simplicity of construction and capacity for equalizinga considerable degree of variation in travel between the cables rendering it highly desirable and efficient for serving itsintended purpose. The essential elements of my invention being more particularly pointed out in the appended claims, it being understood, however, that I intend to include all equivalents of the particular parts recited and intend to embrace all varicured Fig. 3 is a transverse vertical section of the device in a plane indicatedbythe dotted line 3-3 of Fig. 2; I I

Fig. dis a topplan view ofthedevice; and Fig. 5 isa vertical section in a'plane indi-- cated by the dotted line 5''5 of Fig. 4'. Like reference characters indicate like parts-in all the figures of the drawings. First describing briefly the elevator installation illustrated, it; will be understood that the elevator car is suspended by the group of hoisting cables 1, preferably through an equalizing device represented as a whole by the reference numeral 2, which may be of the was bi) type hereinafter described, or of any other suitable type. The hoisting cables travel in the grooves of the hoisting drum 3 at the top of the elevator shaft and are secured at their opposite ends to the counterweight 4. The hoisting cables may be secured to the counterweight directly, as shown, or connected through a suitable equalizing device.

The compensating cables 5 of the installatien, five in number in the present instance,

which are of the same size and. weight, are connected to thelo'ottom of the car by the equalizing device to which the present invention particularly relates, and at the bottom of the elevator shaft engage the grooves of the compensating drum 6 mounted in vertically slidable frame 7 which is weighted to tension the cables, the other end of the cables being secured to the counterweight. It will be understood that whatever their number, the aggregate weight of the compensating cables is the same, or approximately the same, per unit of length, asthe aggregate weight of the hoisting cables. i

The frame of an elevator car of ordinary construction includes, as shown, a pair of vertical stile members 8located one at each siderof the center of the car, and a pair of horizontal channel. iron supporting members 9 secured to the lower endsof the stiles. Above the channels 9 and supported by them and by connection with other parts of the car, is the platform 10' of the car. To provide a secure and sufficient support for my novel equalizing device, I employ a pair of supporting bars 11-11 which are spaced apart a. sufficient distance to receive the equalizing device'between them (see Fig. 3), and aresecurely fastened to the underside of the car frame channel members9. The rear ends of the bars 1111 are furthersupported by a pair of vertical threaded rods 12 secured at their upper ends to the car and at theirlower ends engaging the orificed flanges'of a cross bar 13. the-rods beingequipped with nuts which secure them to the cross bar. 1 i

The frame in which the moving-parts of my equalizing device are assembled as a unit includes a pair of frame blocks 1 l14: which; as shown, may beformed of short sections of channel iron arranged to severally rest upon and bolted. to the supporting bars 11;11 a cross frame bar 15 arranged above and riveted at its opposite ends to thetw'o blocks 14: a pair, of vertical. bracket plates1616 of angle iron-riveted at their top ends through their flanges to-the cross-bar 15; and a'bearingblock 17- arranged aboveand secured to said cross-bar.- Fixed in seats in the lower ends of the bracket plates 16 and in effect forming apart: of the frame workof the devices is a short cylindrical shaft 18 which provides a pivot bearing for a group of paral-' stance, as illustrated, (see FigsB and l) the group consists of five double levers to provide for equalizing the strain of the live compensating cables, and" two of the levers, marked 19, arelongeruthan the remaining three, which are marked 20. Each lever 'consists of a pair of flat bars, a-a, which are connected at their front endsby a cross piece providing for'attachmentto the compensatmg a rounded lower face engaging a seat on the adjacent cross piece of the lever. ,The threaded upperend of the shackle bolts are formed with a keyway to provide a non-rotatable connection of the bolts and the equalizing levers and counteract any tendency of the compensating cables to twist in either direction.

Between the. plates aa of each double equalizing lever is pivoted a lower pulley22, the distance of the axes of the two; pulleys 22 mounted in the longer levers 19 from the axis of the bearing shaft 18 being inthe same proportion to the effective lengthof levers each equipped with nuts 21' and a washer hav- 19 as thedistance of the axes of the-three pulleys, marked 23,-mounted in the shorter levers 2O is to the effective length of. said levers 20, i.e., the stress ratios of all the levers with respect to-the points of attachment of the cables and the pivots of the lower pulleys are the same. :It evidently results from this construction that equal stresses upon the car, sustained through the lower pulleys, whether the pulleys 22 carried by the longer levers 19 or the "pulleys *23 carried by the shorter levers 20 will balance equal opposite stresses acting on the compensating cables through the ends of the levers connected to them. It is further obvious" that the shackle bars, and. also the pulleys, will be disposed inzig-zag or staggered relation to each other; 1

The'bearing' block 17 :before mentioned may conveniently be formed of a metalcast mg cored and machined to provide'suit'able stationary pivot bearings for fourparallel upper pulleys, marked 24, which are arranged obliquely with respect to' the lower pulleys. pulleys and the oscill'atably mounted lower pulleys are connected by an equalizing cable The stationarily mounted upper 25 which is equipped with rope sockets E26- providing'anchorage for'the ends of the cable to the cross frame bar 15'of the device. "From its anchorage at one end the equalizing cable engages the lower and upper pulleys in alternation, the obliquity of the upper pulleys being such as to permit the opposite vertical reaches of the loop of the cable engaging it to track readily in the inclined direction shown to the groovesof the two adjacent lower pulleys which lie below it.

Since the compensating cables are of the same size, the portions below, the. car will in all positions be of the same weight and the stress of gravity of such portions upon the equalizing levers will be the same, while the cables are individually free to assume a higher or lower position as induced by differential travel of the cables upon the equalizing drum arising from the causes before explained, the tension upon the cables being equalized through the equalizing cable and pulleys.

To limit the extent of downward move- I ment of the equalizer levers which might ocour in case of breakage of the equalizing cable, and in such event provide a support for the ends of the compensating cables at a I position a short distance below their normal working position, I provide a safety plate 27 which extends transversely underneath said levers and by a pair of bolts 28 equipped with nuts is securely fastenedto the cross frame bar 15 of the device.

t will be noted that while perfect equalization or distribution of stress among the different compensating cables is attained and at the same time a vertical variation in the position of the ends of the equalizing levers and consequently difference in travel of the compensating cables is permitted, yet the vertical movement of the lower pulleys is small as compared with that of the cable ends, i. e., the movement of the latter is multiplied by the levers; so that agreater variation in travel of the cables is permitted than in the case of equalizers of the cable type heretobody, and an equalizing cable anchored at its ends to said body and engaging said firstmentioned pulleys and second-mentioned pulleys in alternation.

2. In a device for equalizing the strain upon the members of a group of cables connected to a stress-receiving body and subject to joint stress, a plurality of levers severally pivotally connected at one end to said body and severally connected at the other end to said cables, a plurality of pulleys severally tioned pulleys and second-mentioned pulleys in alternation.

3. In a device for equalizing the strain upon themeinbers of a group ofcabl'es connected to a stress-rece1v1ngbody and sub ect to joint stress, a'plurality of parallel horizontally disposed levers severally pivotally connected at one end to said body and severally connected atthe other end to said cables, a plurality of lower pulleys intermediately pivoted to said levers, a plurality of upper )ulleys mounted on said body above said lower pulleys, and an equalizlng cable anchored at itsends to said body and engaging said lower pulleys and upper pulleys in alternation. 1 r i 4. In a device for equalizing the strain upon the members of a group of cables con-,

nected to a stress-receiving body and subject to joint stress, a plurality of levers severally pivotally connected'atone end to said body and severally connected at the other end to said cables, said; levers being partly of one length and partly of another and being connected to the cables in staggered relation, a plurality of pulleys severally intermediately pivoted to said levers at distances from the axes of the levers proportionate to their length, a plurality of other pulleys mounted on saidbody, and an equalizing cable anchored at its ends tosaid body and engaging said first-mentioned pulleys and secondmentioned pulleys in alternation.

5. An equalizing structure according to claim 2 in which the levers therein mentioned consist of a" pair of parallel plates ioo and the therein first mentioned pulleys are severally mounted between the plates of the associated pair.

6. Ina device for equalizing the strain upon the members of a group of cables connected to a stress-receiving body and subject i to joint stress, a plurality of levers severally pivotall connected to said body, the ends of said cab es being equipped with shackle bolts and said bolts being connected to the ends of the levers by an adjustable splined con-.

nection, a plurality. of pulleys severally pivoted to said levers, a plurality of other pulleys mounted on said body, and an equalizing to joint stress, a plurality of levers severally pivotally connected'to'said body, aglurality of pulleyseseverally pivoted to sai levers, said levers being severally connected to said cables at corresponding points of attach- 5 ment with reference to their fulcrunis and the pivots of said pulleys, a plurality of other pulleys mounted on said body, and an equalizing cable anchored at its ends to said I body and engaging said first-mentioned pul- 6 leys and second-mentioned pulleys in alternation.

In testimony whereof, I have subscribed my name. I

WILLIAM P. FROST. 

